It is often desirable to use sport goggles, dive masks and other highly portable transparent eye-protecting shields in environments involving conditions which contribute to condensation build-up on the eye-shield and where even momentary impairment of vision by fogging would be problematic. When the temperature of such an eye-shield has dropped below a dew-point temperature, i.e., the atmospheric temperature below which water droplets begin to condense and dew can form, fogging has occurred and has obstructed vision.
A common characteristic of such portable eye-protecting shields is the fact that they are lightweight enough to be worn on a user's head and are positioned relatively closely to a user's face such that the user's breath and body heat exacerbates fogging conditions. Examples of fog-prone sport goggles intended for use during winter activities have included goggles for downhill skiing, cross-country skiing, snowboarding, snowmobiling, sledding, tubing, ice climbing and the like, and are widely known and widely utilized by sports enthusiasts and others whose duties or activities require them to be outside in snowy and other inclement cold-weather conditions. Examples of fog-prone goggles and eye-shields used in military or tactical environments, including cold weather and other environments, have included ballistics grade goggles used in military or hunting operations, goggles for use in correctional facilities, protective eyewear and goggles for use in police work, crowd control, riot control, or swat operations. Examples of fog-prone dive masks have included eye and nose masks independent of a breathing apparatus, as well as full-face masks in which the breathing apparatus is integrated into the mask. Examples of fog-prone eye-protecting shields have included a face shield that a doctor or dentist would wear to prevent pathogens from getting into the user's mouth or eyes, or a transparent face shield portion of a motorcycle or snow-mobile helmet. Fogging that impairs vision is a common problem with such goggles, dive masks and eye-protecting shields.
There have been various conductive apparatus devised for preventing condensation build-up on eye-shields for eye-protecting shields. The purpose of such prior conductive apparatus has been to provide eye-shields that may be maintained free of condensation so that users would be able to enjoy unobstructed vision during viewing activities. However, without apportionment of the heater on the irregularly-shaped eye-shield lenses of these apparatus, such eye-shields have been subject to problems of creating hot spots on the irregularly-shaped lenses and have not provided for customizable heating of the lenses.
Thus, there have been developed a newer system as disclosed in co-pending U.S. patent application Ser. No. 14/040,683, to Cornelius, for Multiregion Heated Eye-shield, filed 29 Sep. 2013, Publication No. US-2014-0027436-A1 (hereafter also referred to as the “Parent Application”), which is a continuation-in-part of U.S. patent application Ser. No. 13/397,691, to Cornelius, for PWM Heating System for Eye-shield, filed 16 Feb. 2012, which issued as U.S. Pat. No. 8,566,962, issued 29 Oct. 2013 (hereafter also referred to as “the PWM Application”). This newer system has made use of apportioned heaters on an eye-shield, but there has developed the potential problem that the resistivity of the heater from one portion of the heater to another portion of the heater on the eye-shield may be different, and this would also lead to variations in heating across the eye-shield. Further, an additional problem associated with a thin-film heater for eye-protecting shields has been the variations of resistance in the heaters encountered from one eye-shield to another eye-shield.
Before the Parent Application and the PWM Application, no prior eye-shield condensation prevention system had taught a system for employing an apportioned thin-film heating system for evenly heating an irregularly-shaped eye-shield, or alternatively for customized heating of such an eye-shield according to a lens heating profile. Accordingly, the undesirable effects on even, uniform, or otherwise expected, heating, resulting from varied resistance of a thin-film heater across an eye-shield, or from one eye-shield to the next, had not been appreciated until the Parent Application and the PWM Application had been implemented.
The defogging ability of a thin-film heater on an eye-shield is determined by the amount of power supplied to the thin-film heater, the time the power is supplied, and the electrical resistance of the thin-film heater. Thus, variations in resistance of such thin-film heaters have resulted in variations of heating temperatures resulting on the eye-shields, or eye-shield regions, themselves. These variations of resistance have resulted primarily from difficulties experienced in applying the thin-film heating elements uniformly across the eye-shield surfaces, and from difficulties experienced in applying the thin-film heating elements consistently uniformly from one eye-shield to another. Also, different methods applying thin-film heating elements to eye-shields may lead to difference resistance values obtained. Thus, the uneven and inconsistent application of thin film heating elements has created variations in resistivity across the eye-shield regions, and as a result, variations in heat supplied by the thin-film heaters on the respective eye-shield regions.
Such variations in thin-film heater thickness could result, for example, when a thin-film heater has been applied from a single source that is variable in thickness from one region of the source to another region of the same source (e.g., a single roll of PET with an uneven thin-film of Indium-Tin-Oxide (ITO) thereon due to uneven application by sputtering), or perhaps when each region comes from a different source of thin-film heater material (e.g., from two different rolls of PET with varying thickness thin-film heaters on one roll relative to the other roll). Either way, the problem is the same which has led to uneven, or otherwise undesirable, heating characteristics. Accordingly, there have been variations of resistance encountered from one region of an eye-shield to another region of the same eye-shield, or from one eye-shield to another eye-shield in a group, or batch, of eye-shields.
Prior goggles and eye-shields with electronic systems have been primarily used in environments requiring a high degree of portability, that is, where a power source for powering the electronics for the device has been advantageously carried on a strap for the goggle or on the goggle itself, as shown and described in co-pending U.S. patent application Ser. No. 13/519,150, by McCulloch et al., for Goggle with Easily Interchangeable Lens that is Adaptable for Heating to Prevent Fogging.
Some examples of disclosures providing for heating of goggle lenses include the following: U.S. Pat. No. 4,868,929, to Curcio, for Electrically Heated Ski Goggles, comprising an eye-shield with embedded resistive wires operatively connected via a switching device to an external power source pack adapted to produce heating of the eye-shield for anti-fog purposes. The Curcio disclosure does not teach even heating of a lens, or alternatively customized heating of a lens, by employing a certain configuration of thin-film heating material on the lens. Accordingly, Curcio likewise does not teach even and consistent heating of multiple regions of a single lens. Nor does Curcio teach even and consistent heating of one eye-shield to the next eye-shield of a plurality of eye-shields.
US Patent Application No. 2009/0151057A1 to Lebel et al., for Reversible Strap-Mounting Clips for Goggles, and U.S. Pat. No. 7,648,234 to Welchel et al., for Eyewear with Heating Elements, disclose use of thin-film heating elements used for heating an eye-shield with a push-button switch for turning on power from a battery carried on an eyewear band or eyewear arm. Neither Lebel et al. nor Welchel et al. teach even heating of an irregular-shaped lens, or alternatively customized heating of the lens, by employing a certain configuration of apportioned thin-film heating material on the lens. Accordingly, neither Lebel nor Welchel et al. teach even and consistent heating of multiple regions of a single eye-shield or consistent heating of one eye-shield to the next eye-shield of a plurality of eye-shields.
U.S. Pat. No. 5,351,339 to Reuber et al., for Double Lens Electric Shield, recognizes the problem of un-even heating where an electro-conductive film is deposited on an irregular-shaped visor lens and proposes a specific bus bar configuration (electrodes 50 and 60) that addresses the problem of making the distance between electrodes substantially the same for fairly uniform flow of electrical current across the electro-conductive film. However, Reuber et al. does not disclose even heating of a lens, or alternatively customized heating of the lens in accordance with a heating profile, by employing a certain configuration of apportioned thin-filmed heating material on the lens. Further, the eye-shield of Reuber et al. was more uniform than that of a conventional goggle having a cutout portion adapted to fit over the bridge of a user's nose. Accordingly, the configuration of the electrode bus bars of Reuber et al. would not suffice for a more conventional goggle lens configuration. Still further, Reuber does not teach even and consistent heating of one region of an eye-shield to the next region of the same eye-shield, or consistent heating among multiple eye-shields, through the use of an apportioned thin-film heater.
Thus, variations in the thickness of thin-film heaters applied to heat eye-shields to prevent fogging have led to uneven heating over the entire surface of an irregular-shaped eye-shield, and in particular over multiple regions of a single irregular-shaped eye-shield or multiple irregular-shaped eye-shields. Goggles and dive masks, and their eye-shields, are manufactured with an irregular shape required to maintain a position close to the face of the wearer and allowing cutouts for the nose and extended edges for peripheral vision. While various general attempts to evenly heat an eye-shield across its entire surface have been made with serpentine wires included on, or within, eye-shield lenses, as for example in published US Patent Application No. 2008/0290081A1 to Biddel for Anti-Fogging Device and Anti-Fogging Viewing Member, and U.S. Pat. No. 4,638,728 to Elenewski for Visor Defroster, even heating of an irregular-shaped eye-shield, or customized heating of such an eye-shield, with an apportioned thin-film heater, has not been taught in the prior art. Similarly, the prior art has not disclosed even and consistent heating of one region of an eye-shield relative to another region of the same eye-shield, or consistent heating from one eye-shield to the next, despite variable thicknesses of thin-film elements used.
The goggle of Lebel et al. would be susceptible to hot spots, and therefore using such a device in a limited battery-powered application would have unduly discharged the battery. The reason for the hot spots has been because the electrical resistivity between the electrical connections across the resistive elements on the eye-shield has been greater or lesser at different locations on the eye-shield such that the amount of electrical current consumed in the areas with less distance between terminal connections is greater and the amount of electrical current consumed in areas with greater distance between the terminal connections is less. For example, where the terminals are on either side of the lens in a resistive wiring application, there have been problems with evenly heating the lens since the distance the wire has had to travel from one terminal to the other has been greater for those wires traveling over the bridge of the nose and down under the eyes than other wires that travel the shorter distance across a central portion of the lens. To overcome fogging conditions enough power must be applied to overcome the fog in the areas with the greatest distance between the terminal connection points, causing the shorter distance areas to overheat, which in turn has wasted power. Thus, the problem has resulted in limited usefulness of heating of goggle eye-shields. Because of the irregular shape of eye-shields, these problems have existed whether one has considered resistive-wire applications or resistive-film applications.
Still another problem associated particularly with goggles and dive masks is the amount of space provided between the eye-shield portion of the device and the user's face. Where insufficient space has been provided, the wearing of corrective lens eye glasses within the goggle or mask has been prohibited. Further, where excess distance has been provided between the shield portion of the device and the user's eyes, the ability to incorporate corrective lenses into the goggle or mask eye-shield itself has been prohibited. Increased distance between the user's eyes and the eye-shield has improved anti-fogging capability in typical air-flow dependent anti-fog goggles, however, locating the eye-shield at such a great distance from the user's eyes to facilitate anti-fogging has made corrective goggle lenses ineffective for correcting vision, because excessive lens thickness would have been required to accommodate the higher degree of curvature necessary in the lens to make the necessary vision correction. Thus, what has been long needed in the corrective lens goggle, or dive mask, art is a technology that would both permit a corrective eye-shield lens to be sufficiently close to the user's eyes to function properly from a vision correction perspective, but which is also capable of effective fog prevention. Thus, there has developed a need to balance regions of eye-shields to enable even heating of eye-shields across the entire eye-shield surface without excessive use of power or hot spots and without excessive space between the user's eyes and the eye-shield itself for vision correction lens purposes.